In Belgium, as in most countries in Western Europe, the most important conditions of employment for the vast majority of employees in the private sector are regulated by collective agreements. Nevertheless, the content of these collective agreements and the collective bargaining process in Belgium has not yet been the subject of much systematic research on the basis of an explicit scientific frame of reference. The study described here constitutes a first attempt at making the phenomenon of collective bargaining a subject of academic research. Starting with 37 JCs in the private sector, we analysed the content of the collective agreements that were negotiated and measured their relevant institutional, organisational and socio-economic characteristics. This makes it possible to answer questions such as: to what extent does the dominant level of negotiation (sectoral or company level) influence the content of the collective agreement? What effect does the level of organisation of trade union federations and employer federations have on the collective agreements negotiated by them? To what extent do socio-economic characteristics of the sector for which bargaining is taking place - such as the level of competition, sensitivity to exports or the structure of the sector - determine the results of the negotiations? This paper makes a start on coming up with answers to all these questions.